You're a star

5 things you didn't know about the lives of stars

How much do you know about the life and death of stars?



Where are stars born?

A. In a nebula

B. In empty space

C. In the explosion of an old star

D. In a black hole


A. In a nebula. A nebula is a vast cloud of dust and gas. The dust and gas slowly collapse into a star, and nuclear fusion starts in the core. The star is now in its “main sequence” of life.


In the core of a main sequence star, nuclear reactions fuse hydrogen into which element?

A. Carbon

B. Oxygen

C. Helium

D. Iron


C. Helium. For each atom of helium, four hydrogen atoms fuse together. This reaction keeps the star burning for millions — if not billions — of years.


How long does a star’s main sequence last?

A. 10 billion years

B. 80 billion years

C. 20 million years

D. All of the above


D. All of the above. A star’s main sequence lifetime depends on its mass. Our Sun’s main sequence will last about 10 billion years, while a much larger star will only live in its main sequence for 20 million years, and a much smaller star for 80 billion years.


True or False: all stars die by exploding as a supernova

A. True

B. False

C It’s complicated


B. False. Only very large stars, those at least 8 times the size of our Sun, explode in supernovae.


How will our Sun die?

A. It will expand into a red giant, then shrink into a white dwarf

B. It will expand into a red giant and then explode

C. It will collapse as a white dwarf

D. It will explode as a supernova


A. When the Sun runs out of fuel, it will expand into a red giant and engulf the inner solar system. After a few more million years, it will shrink into a white dwarf.

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